The present invention relates to a gas valve driving apparatus of a gas engine, in which any of gas alone, A-heavy-oil (heavy oil of high quality) alone and a combination of the gas and the A-heavy-oil is available as fuel.
Constructions shown in FIGS. 1 and 2 have been known as gas valve driving mechanisms. In FIG. 1, an intake rocker arm 42 engaged with an intake cam 41 is operable to open and close a gas valve 44 as well as an intake valve 43. In FIG. 2, one end of a rocker arm 53 is engaged with a push rod 51 driven by an intake cam 52. Other end of the rocker arm 53 is connected to a sub-rocker arm 55 which is operable to open and close a gas valve 57 as well as an intake valve 56.
However, according to the apparatuses in FIGS. 1 and 2, since the gas valves 44 and 57 are driven by the intake cams 41 and 52, it is impossible to set opening and closing periods of the gas valves 44 and 57 independently with respect to the intake timing, whereby, opening and closing performance of the gas valve is undesirably restricted.
Although, it is not illustrated, there has been still another construction, in which a cam for a gas valve drives an oil hydraulic pump, which drives the gas valve. However, this construction has such disadvantages that the pump, hoses and others occupy a large space and require an expensive manufacturing cost.
Accordingly, it is an object of the invention to provide an improved apparatus, overcoming the above-noted disadvantages, which has a light and simple construction. It is another object to provide an apparatus in which opening and closing periods of a gas valve and a gas feeding period can be set in suitable values for a gas engine.
Other and further objects, features and advantages of the invention will appear more fully from the following description of the preferred embodiments of the invention.